The following steps demonstrate how to assign Geo Types to a dataset field. We are using the
two fields from the join of the Canadian Census dataset: fsa from
canada_census_population_dwellings, and Postal Code from
ca_postal_codes.

Navigate to the dataset that you must modify. Here, we are using the Canadian
Census dataset.

In the Dataset Detail menu, select
Fields.

In the Fields interface, select Edit Fields.

Editing the Fields of Dataset 'Canadian Census'

To specify that the field is a Geo Type, In Edit mode, click the
(down) icon on the right
side of the field, and select the Edit Fields option.

In the Edit Field Parameters window modal, under Geo
Type, select the appropriate option from the menu, and click
Apply. For Fsa, we also changed the
Display Name to Postal Code.

Repeat for the Postal Code field of the table
ca_postal_codes, and click Apply.

Repeat with the Province field of the table
ca_postal_codes, changing the Geo Type to
State/Province. Click Apply.

[Optional] Apply the Geo type to the fields that represent Latitude and Longitude, if they
are not named appropriately.

Under Dataset: Canadian Census, click
Save.

The dataset can now be successfully used for map and interactive map visuals, without further adjustments at the level of the visual.